The first part of this Eeport deals with experiments 

 capable of furnishing definite answers to these questions, and 

 these answers will enable us to draw conclusions with some- 

 thing like exactness as to the means required for dealing 

 with oysters presumably dangerously polluted. The second 

 part of this Report deals in similar fashion with mussels and 

 cockles. In a third part observations and experiments are 

 described which deal with the general question of identifi- 

 cation in oysters of microbes derived from sewage, a question 

 which at present is still imperfectly understood, and on 

 account of this not unfrequently misinterpreted. 



SERIES A. EXPERIMENTS WITH THE B. TYPHOSUS IN 

 OYSTERS. 



Before we enter on a description of the details of these 

 experiments and the methods by which the experiments 

 were carried out, it may not be out of place to give in a 

 general way a summary of the present knowledge concerning 

 this microbe. 



The typhoid bacillus Bacillus typhosus is the essential 

 cause of typhoid or enteric fever ; that is to say, when intro- 

 duced into a susceptible individual generally by way of the 

 digestive organs it is capable of setting up, after an incuba- 

 tion period of from 10 to 14 days, the clinically and patho- 

 logically well-defined acute febrile disease known as enteric 

 or typhoid fever. 



The microbe is found in large numbers multiplying 

 readily in the interior of the ileum and in its swollen mucous 

 membrane, Peyer's glands ; it is found in great abundance in 

 the swollen and inflamed mesenteric glands, and in the 

 swollen spleen. In the intestine, and also in the typhoid 

 stools, its demonstration is somewhat made difficult by the 

 simultaneous presence generally in predominating numbers 

 of other bacteria similar to it, but not the same, to wit 

 Bacillus coli (see below), but it has been shown, and lay some 

 of the most modern methods it has become more easily to do 

 so, particularly during the second and third week of the illness, 



